Deep Water

We know that sea level rise is an inevitable consequence of the global warming that our continued burning of fossil fuels is causing. What we don’t know is how much to expect and how soon to expect it. Journalist Daniel Grossman in his Kindle Single Deep Water: As Polar Ice Melts, Scientists Debate How High Our Oceans Will Rise explores the momentous issue by looking at the work of three scientists who study the past history of elevated sea levels to get a better understanding of what is likely ahead for humanity. Grossman writes from a close acquaintance with climate science and his ability to distil the science in readily understandable form for the general reader is outstanding.

Paul Hearty, “talented and cantankerous”, is a geologist who has argued from his studies of inter-glacial periods that if the Earth warms by two degrees the huge glaciers in Greenland and Antarctica could substantially melt in a short space of time. His field work in the Bahamas and Bermuda, which he regards as a relatively stable region geologically, has led him to the conclusion that in the warm interglacial 400,000 years ago (Stage 11) sea level rose by as much as around 19 metres. Paleoclimatologist Maureen Raymo doesn’t share that view but it was Hearty she invited in 2009 to collaborate in field work with her in Western Australia seeking evidence of sea level rise in the Pliocene. Grossman travelled with them as journalist and gives a lively account of the expedition.

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Polar projections

Arctic vir 2012147

This stunning view of the Arctic and the northern hemisphere was captured by the Suomi-NPP satellite a couple of weeks ago. You can clearly see where the Arctic sea ice is beginning to melt and break up (the bluish bits of offshore ice). More on the image at the Earth Observatory. Meanwhile, new research indicates that extreme Arctic warming and the break-up of the West Antarctic ice sheet may be closely linked, according to evidence from an amazing lakebed core from Russia’s Lake El’gygytgyn ((I’m glad The Climate Show is on sabbatical and I don’t have to attempt to pronounce that…)). From the Science Daily report:

Brigham-Grette, the lead U.S. scientist says, “What we see is astonishing. We had no idea that we’d find this. It’s astonishing to see so many intervals when the Arctic was really warm, enough so forests were growing where today we see tundra and permafrost. And the intensity of warming is completely unexpected. The other astounding thing is that we were able to determine that during many times when the West Antarctic ice sheet disappeared, we see a corresponding warm period following very quickly in the Arctic. Arctic warm periods cluster with periods when the Western Antarctic ice sheet is gone.”

Not good news.

Another Antarctic ice shelf at risk of melt

In the last episode of the Climate Show Gareth drew attention (at 13:40)  to two recent papers suggesting that the Weddell Sea area of the West Antarctic Ice Sheet may be more vulnerable to warming than previously realised. One paper, published in Nature Geoscience, recorded that radar mapping has uncovered a deep sub-glacial basin close to the edge of the ice sheet at the head of the Filchner-Ronne ice shelf. The basin measures 100 by 200 km and is well below sea level, nearly 2km deep in places. The ice sheet, currently grounded above the deep basin, may be more unstable than previously thought and could quickly undergo ice loss.

In a related paper, published in Nature, models reveal that the Weddell Sea region may experience warmer ocean conditions at the end of the 21st century, which could provide the trigger for ice sheet change. Professor Martin Siegert of the University of Edinburgh, who led the project, said:

“This is a significant discovery in a region of Antarctica that at present we know little about. The area is on the brink of change, but it is impossible to predict what the impact of this change might be without further work enabling better understanding of how the West Antarctic Ice Sheet behaves.”

I’ve been reading an interesting collection of expert opinion on the second paper, made available by the New Zealand Science Media Centre (SMC) ; it was gathered by the Canadian SMC.  The seven experts who commented all thought the paper worthy of respect, and together provided a sense of the breadth and liveliness of scientific interest in the behaviour of the ice shelves.  I thought Hot Topic readers might be interested to get the flavour of the comments.

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The Climate Show #27: Aussie hockeysticks, cherry pies and electric planes

It’s a first! Glenn, Gareth and John manage to record a show that clocks in at under an hour — but it’s still packed with interesting stuff. We’ve got news about a new Australasian hockey stick — a paleoclimate reconstruction that demonstrates that the last three decades are the warmest in the last 1,000 years, a look under an Antarctic ice shelf, more methane research, and good news from Greenland. John Cook from Skeptical Science looks at the misuse of temperature records from the Sargasso Sea, and we look at electric planes and boats and the latest version of the solar “leaf”. And… Glenn announces his imminent move to the UK, but never fear, the show will go on — just as soon as he sets up his computer in London (which might be a couple of months).

Watch The Climate Show on our Youtube channel, subscribe to the podcast via iTunes, listen to us via Stitcher on your smartphone or listen direct/download from the link below the fold.

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The Climate Show #26: All the news that fits

Aafter a busy month of harvesting (Gareth) and breakfast broadcasting (Glenn), the Climate Show returns with all the latest climate news: from the thinning of Antarctic ice shelves and the intensification of hydrological cycle (floods and drought, that is) to satellites capturing solar energy and beaming it down to earth, we’ve got it all. And if that weren’t enough, John Cook looks at a new paper that explains the apparent lag between warming and CO2 increase at the end of the last ice age, and tips us off about an excellent outtake from ABC’s recent I Can Change Your Mind about Climate documentary, featuring Naomi Oreskes.

Watch The Climate Show on our Youtube channel, subscribe to the podcast via iTunes, listen to us via Stitcher on your smartphone or listen direct/download from the link below the fold.

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